The present invention relates to a plug-in coupling for removably inter- connecting a first structural member and a second structural member.
Applicant's U.S. Pat. No. 6,206,604 B1 discloses a plug-in coupling comprising a resiliently deformable female coupling part and a male coupling part. The female coupling part is adapted to be inserted into a socket provided at the first structural member such that it is positively retained therein. It comprises a ball-shaped cup, a tubular external wall, and an intermediate annular wall therebetween. The tubular external wall surrounds the ball-shaped cup in spaced relationship thereto and comes into engagement with a peripheral wall of the socket when the female coupling part is inserted into the socket. The male coupling part comprises a ball-shaped head and a fixing portion adapted to be secured to the second structural member.
In this plug-in coupling of the prior art, the intermediate annular wall of the female coupling part, which serves as an insertion guide portion, is of conical shape and is stiffened by webs extending along secants between the tubular external wall of the female coupling part and being connected to the external surface of the ball-shaped cup by radial ribs. The female coupling part is made of thermoplastic elastomeric or rubber material.
This prior art plug-in coupling, which has proven to be very successful in the market, has vibration damping characteristics due to its geometry and the used material so that it provides for vibrational decoupling of the two structural members. However, vibrational decoupling relative movements between the two structural members are limited to directions transverse to the longitudinal axis of the plug-in coupling because the plug-in coupling is relatively stiff in an axial direction due to the above mentioned webs. Use of relatively soft thermoplastic elastomeric or rubber material furthermore suffers from certain drawbacks such as e.g. relatively loose engagement of the coupling parts and reduced thermal dimensional resistance and diesel oil resistance.